Can We Make A Nuclear Reactor That Won't Melt Down?

James Conca
, ContributorI write about nuclear, energy and the environmentOpinions expressed by Forbes Contributors are their own.

NuScale

NRC just approved the idea of walk-away-safe for NuScale’s Small Modular Nuclear Reactor. The small size of its Power Module means it can be factory-built and shipped by truck, deceasing construction costs enormously.

Now, less than a year later, the NRC approved NuScale’s walk-away-safe concept. That means just what it sounds like - the reactor doesn’t need the complex back-up power systems that traditional reactors require and which traditionally add a lot of cost as well as some uncertainty.

This is a big deal. It means the reactor just won’t melt down or otherwise cause any of the nightmares people think about when imagining the worse for nuclear power.

It just shuts down and cools off.

The brain-child of Dr. Jose Reyes, NuScale’s Chief Technology Officer and nuclear engineering professor emeritus at Oregon State University, this modular reactor takes advantage of the small in small modular. The small size and large surface area-to-volume ratio of NuScale’s reactor core, that sits below ground in a super seismic-resistant heat sink, allows natural processes to cool it indefinitely in the case of complete power blackout. No humans or computers are needed to intervene, no AC or DC power, no pumps, and no additional water for cooling (see figure).

NuScale

The first Small Modular Reactor company to file a license application to NRC, NuScale’s Power Module has just gotten approval of it’s walk-away-safe concept. The small size, with its large surface-area-to-volume ratio, prevents any kind of meltdown. If power goes out, the reactor cools over 90% of the heat in the first day by water convection, then 90% of the remaining heat by boiling off the water, then it’s cool enough to slowly bleed what little heat is left off to the surroundings for as long as needed.

A couple of additional features are: 1) no one can hack this reactor and 2) refueling of this reactor does not require the nuclear plant to shut down.

The components of the NuScale reactor can all be manufactured in a factory prior to shipping (see figure) and assembly at the site, removing a major cost issue with building new nuclear plants. The reactor vessels and other large components can be manufactured with medium-sized forges, something we actually have here in the United States. Traditional large reactors need extremely large forging facilities, of which only a few exist in the world - none in America.

Traditional nuclear reactors are between about 600 and 1,200 MW, but these small power modules are about 50 MW each and 12 of them can be put together to make a power plant up to 600 MW - a 12-pack.

These modules use standard 17x17 PWR fuel assemblies, also making them cost-effective, at only half the height, with an average U-235 enrichment of 3.8%. A single NuScale nuclear power module is 76-feet tall and 15-feet in diameter, and sits in a plant covering less than a tenth of a square mile or about 60 acres.

The small size of the NuScale SMR and the absence of large support systems means that the entire power plant covers less than a tenth of a square mile, about 60 acres. The boundaries of this plant are only about 500 yards on a side.

These innovative designs bring the total life-cycle cost to produce electricity with this SMR to below that of most other energy sources, just slightly above hydro and natural gas. This SMR can also be constructed in about half the time of traditional nuclear plants.

NuScale has all its ducks in a row, absolutely critical for a fast review and licensing. They’ve spent $70 million dollars in testing, built large-scale test facilities and built the first 12-reactor Control Room Simulator in the world, at both NuScale’s Integral System Test facility on the Campus of OSU and in at their new offices in Richland, Washington.

The full review will be completed by late 2020, after which NRC will issue a design certification, valid for 15 years, for NuScale to construct this new type of power plant.

The expectation is strong enough that the first commercial NuScale power plant is planned as soon as the review is completed. It will be constructed for the Utah Associated Municipal Power Systems (UAMPS) at the Idaho National Laboratory, operated by the experienced nuclear operator Energy Northwest. This project will take advantage of the reactor’s specific ability to completely load-follow UAMPS wind farms.

Conservative estimates predict between 55 and 75 GW of electricity will come from operating SMRs around the world by 2035, the equivalent of more than 1,000 NuScale Power Modules. And America should lead that effort.

One 50-MWmodule can power a community of 35,000 people without having to connect to a larger grid, essential for isolated regions like islands and military bases that presently depend on fossil fuel. It can be used to provide process heat for industrial applications, or be integrated with intermittent renewables for a combined power plant that is impervious to extreme weather and that can provide zero-carbon affordable electricity 24/7.

This SMR is ideal as the basis of a microgrid. If Puerto Rico had 10 of these plants, they would no longer worry about hurricanes.

‘Small reactors are one of the most promising new nuclear technologies to emerge in decades. There is great potential for small reactors in energy markets—domestic and overseas,’ NEI President and Chief Executive Officer Maria Korsnick said.

NuScale is partnered with Fluor Corporation (NYSE: FLR), a global engineering, procurement, and construction company with a 60-year history in commercial nuclear power.

This nuclear reactor is something that we’ve never seen before – a small modular reactor that is economic, factory built and shippable, flexible enough to desalinate seawater, refine oil, load-follow wind, produce hydrogen, modular to any size, and that provides something we’ve all been waiting for – a reactor that cannot meltdown.

Dr. James Conca is an expert on energy, nuclear and dirty bombs, a planetary geologist, and a professional speaker. Follow him on Twitter @jimconca and see his book at Amazon.com